Almost all consumer level DSLRs and some of the pro level DSLRs come with the built-in flash. Professional photographers who shoot wedding, fashion, commercial portrait, or other special events do not rely on built-in flash to illuminate their subject. But, you don't have to use flash only when there is not sufficient natural light. It can also be used as a fill light to remove shadows or to add a catch light to the subject's eye. One of the best thing about the built-in flash is, you don't have to carry around an extra equipment and is always available on your camera, as long as the camera has sufficient battery power to charge and fire the flash. It can be put to use instantly whenever you want and doesn’t require any sophisticated setup. However, you need to understand few basics settings of your camera and should be comfortable navigating through the menu settings and the buttons on the camera.

Use of camera's built-in flash and its effect on the picture is determined by various settings on the camera, but most importantly, which metering mode you are currently using and what exposure mode you are on play a bigger role. Let's recap these camera metering modes briefly and then we can discuss about the steps we would be following in order to use on-camera flash. Since I wrote the blog about camera metering (in more detail) almost 9 years ago, Nikon has added a new metering mode; Highlight-Weighted Metering, which we will be discussing in the section below.

Nikon DSLR cameras come with the five different shutter sync modes to work with the flash. Not all the exposure modes (S, A, P or M) come with the same flash sync modes but they are available in a slightly different variation depending on which exposure modes you are on. You might want to check your camera manual to find out which sync mode is available in which exposure mode. To change the flash sync mode in your camera, you can hold down the flash button (usually on the front left side of the camera body near the built-in pop-up flash unit) and rotate the main command dial. When I was first learning about these different types of sync modes, they sounded very confusing to me. After reading lots of articles and doing lots of practice on my camera and flash, I got the hang of it. If you are new to flash photography, I am sure it sounds confusing at the beginning. It is simple concept to understand yet confusing sometimes but let me explain them briefly and as clearly as I can. And if you already know about these modes and experimenting a lot with the flash, this might be a topic of interest to you as well.

1. Front Curtain Sync (Normal Sync) - In this mode, camera fires the flash as soon as the front shutter curtain (or first curtain) has been fully raised. It means camera fires the flash as soon as the window for the exposure is opened. Sometimes, it is also called firing the flash at the beginning of the exposure. When your camera is set to the Front curtain sync mode, the slowest (minimum) shutter speed it uses is 1/60th of a second (default to most of the DSLRs which you can change later by going into Flash shutter Speed menu inside the Custom Menu). This shutter speed is also called "Flash Shutter Speed". If your subject is in a low light condition, flash would be the only light for the exposure since the faster shutter speed cuts the ambient light. But if you are shooting with the Normal sync in a bright day light in an Aperture priority mode, your camera will try to use the fastest (maximum) shutter speed defined in "Sync Speed" which is usually 1/250th of a second. If you need a faster shutter speed than the sync speed, you will have to setup an Auto FP High Speed Sync which allows to sync your flash up-to 1/8000th of a second.

Front Curtain Normal Sync

Normally, you should use the Front Curtain Sync when your subject is in a dark condition and flash is the only source of light and you don't care too much about the background. It is also widely used for standard studio setup where your only source of light is the flash light or the studio strobe.

2. Red-eye Sync with Front Curtain - Have you ever noticed a red-eye effect while shooting a portrait? Usually, red-eye is caused by the light from the flash reflecting off the back of your subject's retina. When you are shooting close and with a straight flash, pop-up flash for example, it is very likely that you get the red-eye effect. And if your subject is in dark, red-eye gets worse because of the increased size of the subject's pupils (pupils get bigger to be able to see in the dark).

When you use the red-eye sync mode, depending on which flash system you are working with, camera will try to overcome the issue with a different technique. If you are using an external flash unit, camera fires series of quick light pulse just before the shutter opens. And if you are using a built-in pop-up flash, red-eye reduction is accomplished by illuminating camera's red-eye lamp, which is very bright and might be annoying to the subject. The best way to reduce the red-eye effect is by moving the flash unit away from the camera by using cords or wireless technology.

3. Slow Sync - Slow Sync mode allows you to use the flash to expose your main subject while getting the ambient light to expose the background or surroundings. The standard Slow Sync mode is the front curtain sync mode in which camera fires the flash at the beginning of the exposure and then keeps the shutter open for the ambient light exposure. Normal Slow Sync or Front Slow sync is used mainly when your subject is stationary. For example, if your subject is standing still in front of a building at night, you want to use the normal slow sync to illuminate the subject with the flash and then the shutter will be opened for the ambient exposure to illuminate the background.

Slow Sync Flash Photography

If your subject moves during the exposure, you will get the motion blur due to the long exposure.

Using Slow Sync Normal Flash (ball was moving from the right to the left)

In this mode, since the flash is fired at the beginning of the exposure, it freezes the subject initially but if the subject starts moving while the shutter is still open to capture the ambient light, it produces a motion blur after subject is initially being frozen. Sometimes this can produce an interesting picture with the motion blur but it could be a distraction as well. So, you have to be really careful while using this mode for a moving subject.

4. Slow+Red-eye Reduction Sync - This is a slight variation on the Red-eye reduction sync we discussed earlier. In this mode, flash fires at the beginning of the exposure freezing your subject and keep the shutter open for the ambient exposure. Since this mode is similar to the Normal Sync where flash fires as soon as the shutter is opened, red-eye reduction sync works exactly same as the previous case.

You should use this mode when you want to use on-camera pop-up flash to illuminate the subject and keep the background lit with the slower shutter speed by capturing the ambient light. The problem with this mode can be similar to that of slow sync mode where if subject moves right after the flash is fired, you get the motion blur due to the longer exposure setting (shutter is kept opened after the flash is fired for the exposure).

5. Slow+Rear Sync - This mode works exactly as the Slow sync mode except that the flash is fired at the end of the exposure just before the rear curtain (or second curtain) is closed rather than at the beginning. In this mode, the front curtain is opened first and the camera sensor starts collecting the ambient light and then just before the rear curtain begins to close, the flash fires. In this mode, the term "Slow" refers to the longer shutter speed and the "Rear" refers to the flash firing before the rear curtain closes.

Using Slow Sync with Rear curtain (ball was moving from the right to the left)

This mode is widely used to include the motion blur as an effect rather than a distraction. For example, if you are taking a picture of a moving car (driving forward) using this mode, the shutter opens for the exposure and the car movement creates a blur effect but at the end just before the rear curtain is closed, flash will be fired to freeze the car motion. In this example, the motion blur seems natural giving the sense that car is moving forward leaving nice light trail behind. If we use the normal slow sync in the same scenario, the motion blur occurred at the front of the moving car making it as a distraction (also giving the sense that car is moving backward even though it is moving forward).

When you are using Slow Sync modes, it's best to dial down the flash power to balance the ambient exposure (you can see the ball is little overexposed in both of the examples above). You can test with -1 flash power and do some test shot and then adjust the flash power accordingly for proper balance between the flash and the ambient.

Note : This mode is only available in an Aperture Priority Mode (A) or the Program Mode (P) because these are the only modes where camera controls the shutter speed. But if you are using the Shutter Priority Mode (S) or the Manual Mode (M), you set the shutter speed and the camera can't adjust it independently and hence camera only uses a Rear Sync mode where camera still fires the flash at the end of the exposure just before the rear curtain is closed creating a nice trail effect in a moving subject.

Which Sync Mode should you use?

The most popular and the widely used sync modes are the Normal Sync mode and the Slow+Rear Sync mode. If you do not want the ambient light to contribute to the overall exposure of your photograph but want to expose the subject using the flash light, you should use the Normal Sync mode. And if you want to use the ambient light to expose for the background and the surrounding and illuminate your subject by using the flash light, you should use the Slow+Rear Sync mode. You can also use the Slow+Rear mode if you want to create a motion blur effect on the moving subject. While using Slow+Rear mode, even if motion blur gets produced without your intent, most of the time it gives a nice effect on the photograph rather than being a distraction. Red-Eye reduction methods are rarely used and their effect can be easily corrected during post-processing.

This post is a part of our Q&A section. If you want to submit your question, please use the form in the Contact page.

Ed (Colorado, USA) asked : I have heard the term "dragging the shutter" quite a few times from professional photographer. Do you mind explaining it with an example may be?

When you are shooting at night, you have to deal with different types of lights; flash light (if you are shooting a portrait), street lights and environmental lights. Sometimes you want to shoot without the background objects but there are times when you want to capture the beautiful background scene or nicely lit architecture along with your subject (portrait for example). If you have noticed latest point and shoot cameras or even some entry level DSLR cameras, there is a mode called "Night Portrait" mode which is basically an auto mode. If you turn your mode dial into Night Portrait mode, camera automatically manages the camera settings to capture the portrait along with the background lights. While using one of these auto modes, sometimes you get the good result but sometimes you may need more control over the exposure parameters or the flash mode to get more balanced result. If you want to control the lights and camera settings, you have to step up and dial into one of the semi-manual (S, A and P) or full manual (M) mode and set the parameters accordingly.

You might have used this technique before knowingly or unknowingly and you are just not familiar with the terminology which happens to all of us at some point. It is all about balancing flash and ambient light (light that exist in the environment). When balancing ambient light with flash light, photographers choose camera settings to retain the mood of place, time and environment of shooting. While doing so, we have to allow ambient light by allowing shutter to open little longer (dragging the shutter) and apply the flash light at the end of the exposure (usually to freeze the motion).

Dragging the shutter is very simple and also commonly used technique while doing night portrait photography. It is important to know whether you are using a Manual flash or a TTL flash setting with your camera. If you are using a Manual flash, usually Aperture, ISO, subject distance with the flash and the power of the flash affect flash exposure. Whereas ISO, Aperture and Shutter speed usually contribute to the ambient light exposure. That means you can use the Shutter speed independently to control ambient light exposure only because changing Aperture and ISO will also affect Manual flash exposure. The environmental light (also called ambient light) is continuous source of light but flash light is gone with the blink of an eye which is the main reason why we say Shutter speed doesn't contribute to the flash exposure.

But if you are using TTL flash, those four controls (Aperture, ISO, Distance and the Power) have no control over the flash exposure because your camera and the flash talk to each other based on the Aperture, ISO, distance to the subject and apply appropriate flash power to give the correct exposure. That means you can now use Aperture or ISO or Shutter speed to control ambient light without affecting flash exposure. Using TTL flash is relatively easy and you don't have to remember much while changing camera settings but if you are using Manual flash, you have to be very careful about what setting you have changed because if you change your Aperture, you have to change flash power or ISO or distance to compensate flash exposure but at the same time changing Aperture also affects ambient and hence you may have to adjust Shutter speed too. It's kind of confusing but enough practice clears confusion.

Night portrait

Shutter Speed : 1/60 Aperture : f/4 ISO : 220

Usually dragging the shutter slower than 1/60th of second allows you to register ambient light but you can change shutter speed as you need more and more ambient light. I usually use rear sync flash with slower shutter speed so that your final moment would be frozen.

Dragging the Shutter

Shutter Speed : 1/5 Aperture : f/4.2 ISO : 1600

Dragging the Shutter

Shutter Speed : 1/3 Aperture : f/4 ISO : 800

Shutter Speed : 1/5 Aperture : f/4 ISO : 1600

These images are taken with TTL flash and you can see how changing camera settings is adopted automatically by flash unit and applying appropriate power to properly expose the image.

This post is a part of our Q&A section. If you want to submit your question, please use the form in the Contact page.

Manjit Singh (Delhi, India) asked : Can you please explain me about Depth of Field and it’s relation to the camera settings?

This is what Wikipedia says about DoF - In photography, depth of field (DoF) is the distance between the nearest and the farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DoF, the unsharpness is imperceptible under normal viewing conditions.

Sometimes you want to focus everything inside the frame (for example you are doing landscape photography), and a large DoF is appropriate. And in other cases where you are doing macro photography or portrait photography and want to blur the background, a small DoF may be more effective, emphasizing the subject while de-emphasizing the foreground and the background. Usually, a large DoF is often called deep focus or deep depth of field, and a small DoF is often called shallow focus or shallow depth of field. Now let’s discuss briefly about these terms.

Shallow depth of field: When you selectively focus one part of the image and let rest of the image go out of focus, you will get shallow depth of field. This is pretty famous when you are shooting macro or portrait and want to blur the background or produce nice bokeh in the background.

Deep depth of field: When you want to keep everything inside the frame from the foreground to background in focus using correct combination of camera settings, it is called deep depth of field or larger depth of field.

Deep depth of field

Focal length : 32mm Aperture : F/8 Shutter speed : 8 sec ISO : 200

Now let’s take a look at the camera settings that affect depth of field. The DoF is determined by an Aperture, lens Focal length and the physical distance from the subject.

To get shallow depth of field, you need large opening of the Aperture. And please keep in mind that large opening of Aperture means small f-stop value. Smaller the f-stop value, larger the lens aperture opening will be (allows more light and faster shutter speed) and larger the f-stop value, smaller the lens aperture will be (allows less light and slower shutter speed).

In another word, we can say: for a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DoF; decreasing the f-number decreases DoF.

If we keep the focal length and the distance from the subject fixed: larger the opening of Aperture (small f-stop value), shallower the depth of field you will get and smaller the opening of Aperture (large f-stop value), deeper the depth of field you will get.

2. DoF and its relation to the Focal length

Focal length is something that depends on type of the lens you are using. If you are using zoom lens, you can zoom in and zoom out to increase and decrease lens focal length.

If we keep an Aperture and the Distance from the subject fixed: larger focal length will give you shallower depth of field and smaller focal length will give you deeper depth of field.

3. DoF and its relation to the Distance

Physical distance from the subject to the camera also affects depth of field.

If we keep an Aperture and the focal length fixed: closer you are to the subject, shallower your depth of field will be and farther you are from subject, deeper your depth of field will be.

Conclusion: Larger aperture opening (small f-stop value), closer to the subject and larger focal length will give you the shallowest depth of field possible.